This research will examine the effects of phototherapy as used in neonatal jaundice and shorter wave length light as used in photochemotherapy in drug metabolizing enzymes of the liver and skin of jaundiced and normal rats. We intend to examine the effects of displacement of bilirubin from plasma protein binding sites by sulfadimethoxine in pregnancy of bile duct ligated rats. The interaction of phototherapy, hyperbilirubinemia and selected photodynamic agents including riboflavin and tetracycline will be investigated.